Accused Boston Marathon bomber Dzhokhar Tsarnaev`s older brother, Tamerlan, researched radio transmitters, fireworks and gun stores in the weeks leading up to the 2013 attack that killed three people, a computer expert testified on Tuesday.

Nigeria`s opposition All Progressives Congress (APC) declared an election victory on Tuesday for former military ruler Muhammadu Buhari and said Africa`s most populous nation was witnessing history with its first democratic transfer of power.

Iraqi troops aided by Shi`ite paramilitaries have driven Islamic State out of central Tikrit, Prime Minister Haidar al-Abadi said on Tuesday, but the fight to retake all of Saddam Hussein`s home town continued.